1. Field of the Invention
The present invention relates to epoxysuccinic acid derivatives, and more particularly to epoxysuccinic acid derivatives inhibiting cathepsin B specifically with low toxicity, and the synthesis intermediates thereof.
Statement of the Prior Art
Calcium-activated neutral protease (CANP), cathepsin B and cathepsin L, which belong to thiol proteases, are considered to be associated with the decomposition of the muscular structure protein in malignant muscular atrophy deseases such as muscular dystrophy and distal myophathy.
N-(L-3-trans-carboxyoxirane-2-carbonyl)-L-leucylagmatine [Agric. Biol. Chem., vol. 42, pp. 523-528 (1978)], epoxysuccinyl dipeptide derivatives (U.K. Patent No. 2,046,730) and the like have been heretofore known as the compounds inhibiting several thiol proteases. However, no epoxysuccinic acid derivatives inhibiting specifically only one of the thiol proteases have been known.
As a result of the earnest research to the compounds having an epoxy ring, the present inventors have found that the compounds prepared from the compounds which are included within the structural formula in U.K. patent No. 2,046,730 but are not specifically described in the patent specification, inhibit cathepsin B specifically unlike the known compounds, and have accomplished the present invention.